Date diff in php

How to find the Date difference in PHP?
Any Help link?

function date_diff($earlierDate, $laterDate) {
//returns an array of numeric values representing days, hours, minutes & seconds respectively
$ret=array('days'=>0,'hours'=>0,'minutes'=>0,'seconds'=>0);

$totalsec = strtotime($laterDate) - strtotime($earlierDate);
if ($totalsec >= 86400) {
$ret['days'] = floor($totalsec/86400);
$totalsec = $totalsec % 86400;
}
if ($totalsec >= 3600) {
$ret['hours'] = floor($totalsec/3600);
$totalsec = $totalsec % 3600;
}
if ($totalsec >= 60) {
$ret['minutes'] = floor($totalsec/60);
}
$ret['seconds'] = $totalsec % 60;
return $ret;
}